General Robert Mood of Norway, the head of the UN observer mission to Syria, on Sunday called on all parties to "stop violence" as he arrived in Damascus. "To ensure the success of the plan of (international envoy Kofi) Annan, I appeal to all to stop the violence and help us maintain the cessation of armed violence by all parties," he said.

"We will work to achieve the full implementation of the Annan plan, agreed by the Syrian government. To achieve this, we now have 30 observers on the ground, and we will double that figure in the coming days," he added.

The number of observers is to increase to 100 within a month, before reaching 300, as set out in resolution 2043 adopted unanimously a week ago by the UN Security Council.

According to Amnesty International, the death toll has reached at least 362, since the first team of observers arrived in Syria on April 16.

Upon the arrival of General Mood, the Syrian Observatory of Human Rights (SOHR) counted eight dead in new violence, including four civilians and four soldiers.